When teachers allow you cheat sheets for math tests, in addition to writing down formulas, I recommend writing out examples of problems you don't easily remember the steps to. Whatever you think you'll have trouble recalling during the test, write it down. Sometimes the examples you write down are very similar to questions on the test, which will significantly help you recreate the answers. Also, study your cheat sheet. Do not fill it out and then not review it. If you don't know where to find the information you wrote (quickly during the test), then it's useless to you. Know your sheet!